Steam generator



Oct. 13, 1942. P1 BADENHAUSEN 2,299,050

STEAM GENERATOR Filed Nov. 25, 1939 s Sheets-Sheet 1 juJerZZortwwhww zzemwe Oct. 13, 1942. ,J. P. BADENHAUS EN 2,299,050

STEAM GENERATOR Filed Nov. 25, 1939 3 Sheets-Sheet 3 .7 y gm 4 y ooooaoooo Patented Oct. 13, 1942 STEAM GENERATOR John Phillips Badenhausen, Philadelphia, Pa.,

assignor of one- Incorporated, Ph'ila of Maryland Tito Day and Zimmermann,

elphia, Pa., a corporation Application November 25, 1939, Serial No. 306,051

6 Claims.

This invention relates to steam generators and more particularly to a steam generator adapted for the burning of coal or other fuel, of low volatile content and in pulverized form, for supplying the necessary heat for the steam generation.

Numerous attempts have heretofore been made to burn fuel of low volatile content in small sizes, but many difiiculties have been encountered. The effecting of ignition of the fuel has caused considerable trouble and in the effort to remedy this, in some instances it was found necessary to use mixtures of low volatile and high volatile fuel for the purpose of maintaining ignition. The structure necessary for this purpose greatly increases the cost of installation and of operation and has not been found wholly satisfactory.

In other installations, the low volatile fuel in small sizes has been burned on grates or with stokers in a relatively inefficient manner, the low Volatile fuel being mixed with larger sizes and other kinds of fuel.

In other installations, where an attempt has been made to burn low volatile fuel in pulverized form, difficulty has been encountered with changes of rating, particularly because of the stream-lining of the fuel from the fuel inlet nozzles to the outlet of the furnace chamber.

With prior installations also the carry over beyond the boiler has in many instances been excessive.

Vast quantities of low volatile fuel are available at low cost, but up to this time no wholly satifactory system for utilizing this fuel has been available. The low volatile fuels herein referred to include in the main anthacite coal dust or silt found in the beds of rivers in and near the coal regions and known as river coal, or anthracite dust or silt in waste piles near the collieries, or it may be produced by pulverization of smaller sizes of anthracite coal. Certain bituminous coals are also low in volatile content and these are also available for combustion for the purposes of generating steam in accordance with the present invention. I

The apparatus and methods of the present invention are particularly adapted for overcoming the diff culties which have heretofore been encountered so as to permit of the generation of steam by the burning of low volatile fuels and the operation of the steam generating furnace over a wide range of capacity to meet the fluctuating steam demands found in many industrial plants.

Other advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings forming part hereof, in which:

Figure 1 is a vertical central sectional view taken through the steam generator of the present invention and illustrating a preferred embodiment of the apparatus of the present invention;

Fig. 2 is a front elevational View of the steam generator shown inFig. 1, parts being broken away to show the internal construction;

Fig. 3 is a horizontal sectional view taken approximately on the line 33 of Fig. 1; and

Fig. 4 is a horizontal sectional view taken approximately on the line 4-4 of Fig. 1.

It will, of course, be understood that the description and drawings herein contained are illustrative merely, and that various modifications and. changes may be made in the structure and methods disclosed without departing from the spirit of the invention.

Referring more particularly to the drawings in which a preferred embodiment of apparatus for carrying out the invention is illustrated a chamber is provided having side walls I0 and II, a front wall l2 and a rear wall l3. The chamber is also provided with a top wall [4, including a front portion M a central portion I l and a rear portion |4, as hereinafter more fully referred to.

The bottom of the chamber is closed by well portions, which preferably include a rearwardly inclined portion 15 and a forwardly inclined portion l6 for purposes hereinafter pointed out.

The walls of the chamber are preferably provided with steam generating tubes which may be embedded wholly or partially within the Walls, or the refractory lining thereof, or may, if desired, be exposed.

The chamber is preferably divided, as hereinafter more fully pointed out, into a plurality of spaces or sections in communication successively. The combustion space is preferably divided by a vertically extending dividing wall [1. which is spaced rearwardly from the front wall I2 and extends across the chamber between the side walls l0 and H downwardly from the top wall M toward the lower end of the bottom Wall portion [5, but is spaced therefrom to permit the passage of gases around the lower end of the bafile or wall H. The dividing wall ll thus serves to divide the combustion space into two principal sections, a front or first section A, and a rear or second section B.

An upwardly extending wall or bafile i3 is preferably provided to the rear of the vertical wall I! and across the chamber between the side walls In and II, and constitutes the rear wall of the furnace portion or combustion space of the steam generator. To the rear of the wall I8 a wall 19 is also preferably provided to define with the wall I8 a downward pass for the gases from the furnace section B. Spaced walls 20 and ZI are also preferably provided to the rear of the wall I9 for the purpose of defining an upward pass for the gases. The wall 53, which is disposed to the rear of the wall or baflle 2i, provides therebetween an air preheater space. The lower portion 22 of the preheater space is in communication with the stack (not shown).

The walls of the steam generator are preferably provided with steam generating surfaces as hereinafter more fully pointed out, the steam generating portions of the structure and the furnace being integral. The side walls It and II are preferably each provided with an upper side wall header 25 and lower side wall headers 25 and 21.

A bank of tubes 28 extends from the lower side wall header 26 to the upper header 25, the tubes being relatively widely spaced and separated to an extent such that the walls II] and II will not be unduly cooled, as hereinafter more fully pointed out.

A bank of tubes 29 is also provided between the lower side wall header 2? and the upper header 25, the tubes of the bank 29 being spaced rather closely. An upper front wall header 30 is provided at the junction of the front wall l2 and the front section I l of the top wall I4, and an upper header 3| is also provided at the junction of the front section I4 of the top wall I4 and the wall or baffle IT.

A bank of tubes 32 is provided between the upper header 36 and the upper header 3 I. Alower header is provided preferably at approximately the same elevation as the side wall header 2'! and a bank of tubes 35 is provided which extends upwardly along the inclined section l5 of the bottom wall and then upwardly along the front wall I2 to the upper front wall header 30.

Banks of tubes 31 are also preferably provided for connecting the lower side wall header 26 to the lower header 35. The lower header 35 is also preferably connected to the upper header 3I by banks of tubes 33, 39 and 40 which are disposed on each face of the wall or bafile I1, and on the face thereof toward the front wall I2 are preferably spaced a sufficient distance apart so as not to unduly cool the wall or bafile IT. The lower ends of the tubes of the banks-of tubes 38 and 40, below the wall I I, are preferably offset from their locations on each side of a straight tube 39 to a position in alinement therewith (see Fig. 4) and then are bent back to positions corresponding to their original locations at the place of connection to the lower header 35.

A lower drum 42 is provided preferably to the rear of the downward pass and this drum 42 is connected by a bank of tubes 43 to the lower side wall header 21. The lower drum 42 is also preferably connected by suitable tubes 44 to the lower header 35.

An upper steam and water drum 45 is provided and a bank of tubes 46 lining the inside of the top wall Ni are provided and extend from the upper header 3! to the drum 45. Banks of tubes 47 are also provided between the side wall headers 25 and the drum 45 and an additional bank of tubes 43 is provided extending from the lower drum 42 forwardly and then upwardly within the wall I8 and to the upper drum 45. The wall or baffle I 9 is similarly provided with a bank of tubes 49 and the wall or bafile 20 is likewise provided with a bank of tubes 58 which extend from the lower drum 42 to the upper .drum 45. The upward pass between the wall or baffle 20 and the wall or bafiie 2| is also provided with a bank of tubes 5| which may serve as downcomer tubes and which extend between the lower drum 42 to the upper drum 45.

Superheater headers 52 are provided and are connected by a bank of tubes 53 to the steam space of the upper drum 45. The superheater tubes 54 preferably extend downwardly and then upwardlywithin the downward pass between the rear wall I8 of the furnace section and the wall or baffle 19 and are connected to a superheater header 55 for delivery of the steam.

The upper drum 45 is also connected to the lower drum 42 by a bank of downcomer tubes 56 which are preferably disposed to the rear of the wall I3.

The front section A of the furnace is provided with suitable structure for introducing fuel and air therein, and for this purpose and in connection with the burning of the fuel of low volatile content a plurality of nozzles BI] are provided for supplying the fuel in separated streams together with a limited quantity of air. The nozzles Bil are preferably mounted on the front section I 4 of the top wall I 4 and preferably intermediate the front wall I2, and the wall or baflle I'I. These nozzles may be of any suitable type for the delivery only of the fuel or for the delivery of the fuel in an air stream. The air is, however, preferably introduced around the respective streams of coal and is supplied through the inlets 6| from the duct 62 and the duct 63 which are connected as illustrated.

Provision is also made for introducing air to the lower portion of the front section A of the furnace chamber from the duct 54, which is connected to the duct 63, through a plurality of slots 65, 66 and 61, which are provided along the front wall I2. The slots 65, 66 and 6? may be provided with individual dampers 68 for controlling the air flow therethrough. While any preferred arrangement of slots may be used, it is .desirable, as illustrated in Figs. 1 and 2, to provide the slots at a plurality of levels and substantially across the entire front wall I2 of the furnace. The slots are, of course, disposed in such a manher that they extend through the walls between tubes of the bank of tubes 35. The slots are preferably of an area such that the major portion of the air required for the combustion of the fuel can be introduced therethrough.

The air heater 10 preferably has a forced draft fan (not shown) connected to the air inlet side thereof in the manner well known in the art, and the rear portion of the furnace and beyond the gas outlet of the air heater I8 is also connected in the manner well known in the steam generating field to an induced draft fan (not shown) and thence to the stack (not shown). The preheated air from the air heater I0 is delivered to the duct 63 and thence to the air inlets as heretofore described.

The methods of burning low volatile fuel in pulverized form in accordance with the present invention and the preferred mode of utilization of the apparatus illustrated will now be pointed out.

Goal of low volatile content and in fine sizes or reduced by suitable pulverizing mills and corresponding to those frequently referred to as anthrafines is supplied to the nozzles. A limited quantity of preheated air is supplied from the preheater through the duct 63 and the duct 62, and is delivered to the furnace at the place where the finely divided fuel is introduced and with the fuel.

It is, of course, known that in a suspension of coal in air the ratio of the air to the coal affects the velocity of flame propagation in the mixture and also that upon an increase of that ratio of propagation velocity increases to a maximum and then decreases with a further increase of the air to coal ratio. Other factors such as volatile content, temperature, particle size, ash content and moisture content have an effect upon the pro pagation velocity. With anthracite and other low volatile fuels in air suspensions the maximum velocities are much lower than with bituminous fuels and the air-coal ratios for maximum velocities with powdered anthracite lie in the range of approximately 0.5 to 0.8.

The quantity of air introduced at the nozzles 60 with the low volatile fuel is accordingly relatively small as compared with the quantity of air required for the complete combustion of the fuel and is preferably maintained within the range indicated.

The restricted quantity of air introduced at and around the nozzles 60 is sufficient to permit of ignition of the fuel, but is not sufiicient in quantity to permit of chilling the fuel to the point where ignition is prevented. The ignition of the fuel is completed inthe downward passage of the fuel from the nozzles 60 and within the first furnace section A, and the combustion of the ignited fuel is advanced and carried to completion by the use of the additional quantities of preheated air which are introduced through the slots 65, 66 and 61 in the front wall I2. This combustion continues within th second furnace section B and during the upward passage within the space between the side walls I0 and H and the dividing wall I! and the wall IS. The heat release within this section of the furnace is relatively high.

The provisions for extracting heat for steam generation and thus cooling the front wall l2, the front portions of the side walls [0 and II and the partition I! are preferably such that these walls are not cooled unduly, but will be maintained during operation at a temperature sufficient to assist in the ignition and continuation of the ignition as the fuel passes downwardly within the front section A of the furnace chamber.

A portion of the heat released in the front section A of the furnace chamber is utilized for steam generation in the banks of tubes 28, in the side walls I0 and H, respectively, the bank of tubes 36 in the front wall I2, and the banks of tubes 38, 39 and 40 on the front face of the partition wall IT. The major portion of the heat released is absorbed in other portions of the steam generator, and more closely spaced tubes are provided in the side walls Ill and II, as illustrated by the banks of tubes 29 and in the wall I8, as illustrated by the banks of tubes 48.

The lower portion of the front section A of the furnace chamber and the lower portion of the rear section B of the furnace chamber are so shaped as to assist in the discharge to the lower part of the rear section B of the furnace chamber of any ash or other solid material for removal, as desired.

As the combustion is completed, the gases pass from the furnace section B and then downwardly and in contact with the superheater tubes 54. The gases then pass upwardly in the upward pass in contact with the tubes of the bank of tubes 51. Any ash which is carried over from the furnace chamber and which settles into the collecting space below the drum 42 may be removed, as desired.

The hot gases then pass downwardly through the air heater 10 for delivering up portions of the heat remaining therein to the air which is used for supporting combustion. The steam generated in the walls is delivered to the drum 45, from the drum 45 to the superheater headers 52, to the superheater tubes 54, and then to the superheater header 55 from which it is delivered in the usual manner.

I claim:

1. In apparatus for the combustion of fuel of low volatile content for steam generation, a furnace chamber having enclosing walls, a vertical downwardly extending dividing wall in said furnace chamber separating said furnace chamber into a downward pass section and a communicating upward pass section, said sections being of unequal volume, the smaller and downward pass section constituting an ignition chamber section and the larger and upward pass section constituting a combustion chamber section, means for supplying low volatile fuel into said ignition section, means for supplying a limited quantity of air with said fuel for ignition thereof, means at the lower portion of the furnace chamber for supplying air for the combustion in the combustion section of the ignited fuel from the ignition section, the walls of said sections being lined with steam generating tubes, the effective heat absorbingsurface of the tubes of the ignition section being substantially less than that of the tubes of said combustion section, whereby the ignition of the fuel will be maintained until the combustion of the fuel is effected in said combustion section.

2. In apparatus for the combustion of fuel of low volatile content for steam generation, a furnace chamber having enclosing walls, a vertical downwardly extending dividing wall in said furnace chamber for separating said furnace chamber into a downward pass section and a communicating upward pass section, said sections being of unequal volume, the smaller and downward pass section constituting an ignition chamber section and the larger and upward pass section constituting a combustion chamber section, means for supplying low volatile fuel into said ignition section, means for supplying a limited quantity of air with said fuel for ignition thereof, means at the lower portion of the ignition section for supplying air for the combustion in the combustion section of the ignited fuel from the ignition section, the walls of said sections being lined with steam generating tubes, the efiective heat absorbing surface of the tubes of the ignition section being substantially less than that of the tubes of said combustion section, whereby the ignition of the fuel will be maintained until the combustion of the fuel is effected in said combustion section.

3. In apparatus for the combustion of fuel of low volatile content for steam generation, a furnace chamber having enclosing walls, a vertical downwardly extending dividing wall in said furnace chamber for separating said furnace chamber into a downward pass section and a communicating upward pass section, said sections being of unequal volume, the smaller and downward pass section constituting an ignition chamber section and the larger and upward pass section constituting a combustion chamber section, means for supplying low volatile fuel into said ignition section, means for supplying a limited quantity of air with said fuel for ignition thereof, means at the lower portion of the ignition section for supplying air in a plurality of separate downward streams for the combustion in said combustion section of the ignited fuel, the walls of each of said sections being lined with steam generating tubes, the effective heat absorbing surface of the tubes of the ignition section being substantially less than that of the tubes of said combustion section, whereby the ignition of the fuel will be maintained in said ignition section untilthe combustion of the fuel is effected in said combustion section.

4. In apparatus for the combustion of fuel of low volatile content for steam generation, a furnace chamber haying a vertical front wall and avertical rear wall, at least one of said walls having a lower inwardly inclinedportion, a discharge space at the lower part of. the furnace chamber to which solid residues are directed by said inclined portion, a vertical downwardly extending dividing wall in said furnace chamber separating said furnace chamber into a downward pass section and a communicating upward pass section, said walls being spaced to provide unequal sizes of said sections, the downward and smaller, of said sections constituting an ignition chamber and the larger and upward of said sections constituting a combustion chamber, means for supplying low volatile fuel into said ignition section, means for supplying a limited quantity of air with said fuel for ignition thereof, means at the lower portion of the ignition section for supplying air for the combustion in the combustion section of the ignited fuel, the

walls of each of said section being lined with steam generating tubes, the effective heat absorbing surface of the tubes of the ignition section being substantially less than that of the tubes of the combustion section, whereby the ignition .of the fuel will be maintained in said ignition section until combustion of the fuel is effected in said combustion section.

5. In apparatus for the combustion of fuel of low volatile contentfor steam generation, a furnace chamber having a vertical front wall with a lower inwardly'inclined portion and a vertical rear wall with a lower inwardly inclined portion, a discharge space at the lower part of the furnace chamber to which solid residues are directed by said inclined portions, a vertical downwardly extending dividing wall in said furnace chamber separating said furnace chamber into a downward pass section and a communicating upward pass section, said walls being spaced to provide unequal sizes of said sections, the downward and smaller of said sections constituting an ignition chamber section and the larger and upward of said section constituting a combustion section, means for supplying low volatile fuel into said ignition section, means for supplying a limited quantity of air with said fuel for ignition thereof, means at the lower portion of the ignition section for supplying air for the combustion in the combustion section of the ignited fuel, the walls of said section being lined with steam generating tubes, the effective heat absorbing surface of the tubes of the ignition section being substantially less than that of the tubes of the combustion section, whereby the ignition of the fuel will be maintained in said ignition section until combustion of the fuel is effected in said combustion section.

6. In apparatus for the combustion of fuel of low volatile content for steam generation, a furnace chamber having a vertical front wall with a lower inwardly inclined portion and a vertical rear wall with a lower inwardly inclined portion, a discharge space at the lower part of the furnace chamber to which solid residues are directed by said inclined portions, a vertical downwardly extending dividing wall in said furnace chamber separating said furnace chamber into a downward pass section and a communicating upward pass section, said walls being spaced to provide unequal sizes of said sections, the downward and smaller of said sections constituting an ignition chamber section and the larger and upward of said sections constituting a combustion chamber section, means for supplying low volatile fuel into said ignition section, means for supplying a limited quantity of air with said fuel for ignition thereof, means at the lower portion of the front wall of the ignition section for supplying air for the combustion in the combustion section of the ignited fuel, the walls of said sections being lined with steam generating tubes, the effective heat absorbing surface of the tubes of the ignition section being substantially less than that of the tubes of the combustion section, whereby the ignition of the fuel will be maintained in said ignition section until combustion of the fuel is effected in said combustion section.

JOHN PHILLIPS BADENHAUSEN. 

